This invention is directed to a bipolar crossed-field switch device wherein potential may be applied in either direction for on-switching, or current can flow in either direction for off-switching of the switch device.
R. J. Harvey, U.S. Pat. No. 4,071,801 describes a crossed-field switch device having a single interelectrode space or gap, with control of the magnetic field causing off-switching. That patent describes an improvement over the general background. H. E. Gallagher and Wolfgang Knauer are inventors of U.S. Pat. No. 3,906,270 and U.S. Pat. No. 3,963,960. Both of these are directed to bipolar structures. Gallagher and Knauer, U.S. Pat. No. 3,906,270 describes a single gap crossed-field switch device wherein the magnetic field is shaped to provide for substantially uniform conduction in either polarity. That patent also identifies the early prior art in crossed magnetic and electric field devices, such as those in the Penning U.S. Pat. No. 2,182,736 & Boucher U.S. Pat. Nos. 3,215,893 and 3,215,939. On the other hand, Gallagher and Knauer, U.S. Pat. No. 3,963,960 is directed to a two interelectrode gap device, one having three electrodes, and it identifies in its background the G. A. G. Hofmann et al., U.S. Pat. No. 3,641,384 patent which has a three electrode structure with two interelectrode spaces. The R. J. Harvey and the two Gallagher and Knauer U.S. patents identified above are incorporated herein in their entirety, including their background references, by this reference.
These patents point up the difficulty of providing a structure wherein the physical process produces the plasma with sufficient uniformity in each direction that bipolar on-switching, conduction and off-switching can be achieved. Such is necessary where the crossed-field switch device is applied in an alternating current circuit, particularly a high speed circuit which can be actuated in a fraction of a cycle. Such structures are necessary for increasing the impedence in faulted alternating current high voltage lines.